This invention relates to a process for the production of mixtures of novel organofunctional alkoxysilanes by the reaction of mixtures of certain substituted organic halides and chlorosilanes with molten sodium dispersed in alkoxysilanes. In the described process, the substituted organic groups of the organic halide replace alkoxy groups of the alkoxysilanes.
The literature contains many examples of the reaction of sodium with chlorosilanes. For example, it is commonly known that sodium reacts with chlorosilanes to form polysilanes and sodium chloride. Sodium also reacts with organic halides by the well known Wurtz reaction which can be written in equation form as: EQU 2RX+2Na.fwdarw.2NaX+RR (1)
Our work has shown that molten sodium may be dispersed in alkoxysilanes at about 100.degree. C. and little reaction can be observed in many hours. Ryan, J. W., J. Amer. Chem. Soc. 84:4730-34, 1962, demonstrated that at more elevated temperatures, reduction of alkoxysilanes occurred to form alkylsilanes.
When molten sodium was dispersed in refluxing tetramethoxysilane at 122.degree. C., 24 percent of the tetramethoxysilane was converted to methyltrimethoxysilane in 84 hours. Ryan, supra, proposed that this conversion proceeded through the following two step process: EQU (MeO).sub.4 Si+2Na.fwdarw.(MeO).sub.3 SiONa+Na--CH.sub.3 ( 2) EQU (MeO).sub.4 Si+Na--CH.sub.3 .fwdarw.MeSi(OMe).sub.3 +NaOMe (3)
Our work has shown that molten sodium dispersed in PhSi(OMe).sub.3 at 125.degree. C. for 72 hours formed nine percent phenylmethyldimethoxysilane in a similar manner.
British Patent 573,906, issued Dec. 12, 1945, to Revertex, Ltd., teaches that the dropwise addition of iso-amyl bromide to a dispersion of molten sodium in a solution of tetramethoxysilane formed iso-amylSi(OMe).sub.3 and (iso-amyl).sub.2 Si(OMe).sub.2. Other examples taught that the same procedure formed substituted ethoxysilanes when chlorobenzene, cyclohexylbromide, benzyl chloride, ethyl bromide, or n-octyl bromide was added to a dispersion of molten sodium in tetraethoxysilane.
Tiganik, L., U.S. Pat. No. 2,521,267, issued Sept. 5, 1950, claimed a method of reducing the consistency of the mixture of products obtained by bubbling a gaseous mixture of tetrachlorosilane and methylchloride into a stirred dispersion of molten sodium in tetraethoxysilane activated by a small amount of copper, tin, or silver. In this process, all of the methyl chloride was absorbed. Distillation after filteration gave about an 85% yield of principally MeSi(OEt).sub.3 with some Me.sub.2 Si(OEt).sub.2 and a very small quantity of Me.sub.3 SiOEt. This patent claimed the method in which an alkyl chloride is added as a mixture with an acid substance, such as tetrachlorosilane, in order to quickly neutralize the sodium alkoxide formed during the reaction making the reaction product more easily filterable.
Tiganik, L., British Patent 668,532, issued Mar. 18, 1952, claims a method for reducing the consistency of products formed when ethyl bromide is added to a dispersion of molten sodium in tetraethoxysilane. High consistency makes stirring the reacting dispersion of molten sodium very difficult and makes filtration of the end mixture nearly impossible. The patent teaches that the high consistency of the mixture is due to the presence of NaOEt and that filtration is facilitated by acidifying the final mixture with SiCl.sub.4, HCl, acetic anhydride or any other acidic substance.
Tiganik, L., Canadian Patent 598,444, issued May 24, 1960, teaches a process in which 400 moles of chlorobenzene mixed with 100 moles of tetrachlorosilane was added to molten sodium dispersed in tetraethoxysilane. Decomposition of the sodium alkoxide compound formed in the reaction is effected by carrying out the reaction in the presence of tetrachlorosilane.
Chappelow, C., et al., U.S. Pat. No. 2,986,687, issued May 23, 1961, claims a process whereby a tertiary lower alkyl halide mixed with a chlorosilane is added to an alkoxysilane in the presence of sodium, at 115.degree. C. and with vigorous stirring, to make tertiary alkylalkoxysilanes. The alkoxysilanes employed as reactants were of the general formula R.sub.a Si(OR')4a; where R and R' were selected from a group consisting of alkyl, aryl, substituted alkyl, and substituted aryl radicals. When R or R' was a substituted alkyyl or aryl hydrocarbon radical the substituent was selected from the group consisting of alkoxy, aryloxy, alkyl-thio, arylthio, dialkylamino and trialkylsilyl groups.
The instant invention is a process using certain substituted organohalides to make a variety of organofunctional alkoxysilanes. The instant invention also includes a variety of novel organofunctional alkoxysilanes capable of being prepared by the described process. The claimed organofunctional alkoxysilanes are useful in forming copolymers and as coupling agents.